Simultaneous study of the metabolic turnover and renal excretion of salivary amylase-125I and pancreatic amylase-131I in the baboon

Abstract

A B S T R A C T The metabolic turnover of salivary and pancreatic amylase was studied in the baboon, an animal with a serum amylase level and renal clearance of amylase similar to man. Purified amylase was electrolytically iodinated. Although iodinated and uniodinated amylase had similar gel filtration, electrophoretic, enzymatic, glycogen precipitation characteristics, the labeled enzyme was cleared less rapidly by the kidney than was the unlabeled material. However, urinary iodinated amylase which had been biologically screened by the kidney had a renal clearance and serum disappearance rate indistinguishable from unlabeled amylase and thus can serve as a tracer. in metabolic turnover studies. Administration of a mixture of salivary amylase-'I and pancreatic amylase-1I made it possible to simultaneously measure the serum disappearance and renal clearance of these two isoenzymes. The metabolic clearance of both isoenzymes was extremely rapid with half-times of about 130 min. This rapid turnover of serum amylase probably accounts for the transient nature of serum amylase elevation which frequently occurs in pancreatitis.Pancreatic amylase-"I was consistently cleared more rapidly (mean clearance ratio: 1.8) by the kidney than was salivary amylase-'I. This more rapid renal clearance of pancreatic amylase may help to explain the disproportionate elevation of urinary amylase relative to serum amylase observed in pancreatitis.

Differences in the Renal Handling of Pancreatic and Salivary Amylase in the Rat

“…These findings are in agreement with former observations on amylase excretion in the baboon [3], but not with those in humans [6,7], They fit the theory of protein excretion, according to which size and charge are impor tant determinants of glomerular filtration of proteins [15,16]. The difference in the reab sorption rate, however, is unlikely to be caused solely by differences in molecular charge [17][18][19], Thus, Wetzels et al [7] re ported on a higher renal clearance of P-(pi 7.0) than of S-amylase (pi 5.9-6.4) in hu mans.…”

Amylase activity in human bile.

“…Deficiency of the essential amino acid tryptophan, diminished amylase production, and administration of puromycin, a specific inhibitor of protein synthesis, caused a cessation of amylase production by the liver. In the dog, the liver appears to produce amylase (Nothman and Callow, 1971), and, in the baboon, Duane et al (1972) showed that the liver was a major site of amylase destruction.…”

Serial Changes in Serum Levels of Pancreatic Isoamylase, Trypsin and Elastase 1 after Surgical Interventions to the Pancreas

“…The reason for the delayed return of elastase 1 to its normal level in comparison with amylase remains unclear. The half-life of amylase has been reported to be 1-4 h in experimental studies [13][14][15][16], Elas tase 1 exists in the blood in a complex form either with ai-antitrypsin or with cti-macroglobulin [17]. The ai-Antitrypsin-bound form of elastase 1 was measured with the radioimmunoassay technique used in the present study [ 18].…”